Variable resistance



Jan. 1, 1929. 1,697,829

H. P. DONLE VARIABLE RESISTANCE Filed May 20, 1925 QJGMMQQ ATTORNEY Patented Jan. 1', 1929.

UNITED STATES PATENT OFFICE.

VARIABLE RESISTANCE.

Application filed Kay 20, 1925. SerlaLNo. 31,522.

My invention relates to a variable resist plane of the line 44 of Fig. 3, parts being ance of the compression type. i broken away.

It is the general object of the invention to In said drawings 5 indicates abody memprovide an improved and simplified form of her of insulating material, this body being 5 variable resistance of the compression type. preferably provided with a recess or hous- The invention resides in certain combinamg aperture 6 for the reception of parts to tions and details of construction hereinafter be later described. In the bottom of the 60 described. housing there may be a metallic plate 7 con- Briefly stated, in the preferred form of nected as by means of a screw 8 to a Wire terthe invention I employ a body of insulating minal 9 extending to the outside of the housmaterial having a suitable recess therein for ing for, connection to a conductor. At the the reception of the compression resistance bottom of the body member is a base'plate 10 65 member. A wire terminal is electrically coninsulated from the terminal member 9 as by nected to one side of said resistance member means of an insulating disk 11 interposed and extends to the outside of the body Inembetween those parts. The base plate 10 may her. A base plate and a face plate are posihave a second wire terminal 12 integrally tioned at opposite sides of the insulating formed thereon. A face plate 13 fits on the .70

body member and are electrically and mebody member and serves to close the recess, chanically connected together as by means of 6. Connecting-members such as bolts 14-14 bolts. A screw or the like engaging a threadpass through suitable passages in the body ed sleeve on one of said plates serves to commember and mechanically and electrically press the resistance member and the bolts or connect the two cover plates 10 and 13 to other connecting links between the base plate each other. and face plate serve to take the stress of the The face plate 13 may have a sleeve 15 se- 25 compression screw off of the insulating body cured thereto in any suitable manner and member and causes that stress to be taken by this sleeve is preferably threaded externally said two plates and their mechanical conat 16 for the reception of the nut 17 for senectirig means. One of these cover plates is curing the entire assembly to a panel-as will provided with a second wire terminal which be clear from Fig. 1. The sleeve 15 is thread is electrically connected with the opposite ed internally for the reception of the comside of the resistance member. A spring may pression screw 18 which extends through the be employed for progressively applying the sleeve and into the recess 6 in the body lnCllL- force of the compression screw to the resisther. A knurled nut or the like 19 serves as ance member and if desired a second spring a convenient means for rotating' the screw 35 may be employed for constantly urging the for moving the same inwardly or outwardly. screw in one irection so as to take up the A compression resistance member 20 is lobacklash. The entire device may be secured cated in the recess 6 and is electrically conto a panel or the like by means of a single nected at one side to the plate 7 and wire ternut or by means of screws passing through minal 9. In the preferred form I interpose a 4o ears on one of the cover plates. 7 plate 21 of silver plated brass or the like be- In the drawin s which show for illustratween the resistance member 20 and the tive purposes only, a preferred form of the plate 7 which latter plate may also be silver 05 invention: plated if desired. A second plate 22 of silver Fig. 1 is a side view in elevation of a va-, plated brass or the like preferably rests on' 46 riable resistance embodying features of my top ofthe compression member 20., While invention; it is not necessary to em loy silver plates as Fig. 2 is a top plan view of the variable herein described, it is euite desirable for the resistance shown in Fig. 1, a part being reason thatthe oxide 0 silver is itself a good broken away; conductor and, therefore, should the arts 50 Fig. 3 is acentral sectional view taken subbecome oxidized the utility of the variable stantially in the plane of the line 33 of resistance would not be materially impaired. Fi 4; p I employ resilient means for effecting a ig. 4 is a view taken substantially in the progressively increasing pressure on the re- In the form shown a bowed spring 28 is mon ledges 25-25 formed the recess 6. This plateterposed between the upper plate 22 and the screw 18. Now when'the screw is moved inwardly the spring 23 is deflected and puts a progressively increasing pressure upon the resistance member and thus increases the distance through which the screw 18 and conse quently the knob 19 must be rotated to produce the maximum compression of the resistance block.' If the screw 18 acted directly upon the plate 22 the entire range of adjustment of the resistance would be a mere fraction of a turn of the screw 18.

Now in order to take up the back lash in the screw, a plate spring 24 may be seated in the body member at opposite sides of spring 24 acting beneath the screw 18 serves to constantly urge the same outwardly so that any back lash in the screw will be taken up, thus reducing to a minimum the variation of the instrument.

The operation of the device will now be clear. The entire assembly may be secured on a panel as by means of the nut 17 as clearly shown in Fig. 1, or if desired, the base plate 10 may have ears 26-26 for receiving screws or the like forpositioning the assembly on a suitable base. When the screw 18 is moved inwardly the. plate spring 24 takes up the back lash and the screw in moving inwardly stresses the spring 23 which in turn acts on the plate 22 so as to compress the resistance member 20.

In devices of this character the conductivity is determined by the extent of compression of the resistance member. The current flow through the device may be through the terminal 9, screw 8, plate 7, plate 21, resistance member 20, plate 22, springs 23 and 24, screw 18 to the face plate 13. From the face plate 13 current is conducted through the bolts on other connecting members 14 to the base plate 10 and thence to terminal 12.

It will be seen that in a construction as herein described considerable force is exerted on the compression member and supporting parts by the screw 18. It is, therefore, quite desirable to have the base plate 10 and the face plate 13 connected to .each other as by means of the bolts 14 as by this construction substantially the entire force of the screw 18 is taken by the two cover plates and the screws 14 and the insulating body member is not substantially stressed.

The resistance member may be made so as to ranges.

While the invention has been described in detail, I do not wish to be confined to the specific form shown sincechanges may be made within the scope of the invention as defined in the appended claims."

I claim:

1. In a device of the character described, an.

insulating body member, a metallic base plate at one side thereof, a metallic face plate at the opposite side, said body member having a recess therein, .a resistance member in said recess, bolts extending through said insulating body member at opposite sides of said resistance member for electrically and mechanically connecting said plates to each other and means for compressing said resistance member, a terminal electrically connected to one side of said resistance member and a terminal electrically connected to the opposite side of said resistance member through said through bolts for connecting said base and face plates.

2. In a device of the character described, an insulating body member having a recess therein, said body member having supporting ledges at opposite sides of said recess, a compression resistance member in said recess, a screw for compressing the resistance member, a plate spring resting on the ledges in said body member for urging said screw in one direction to take up back lash and a bowed spring at one side of said resistance mem her for causing a progressively increasing pressure to be applied to the compression member by the screw.

3. In a device of the character described, a body member of insulating material and having a recess therein, a metallic plate in said recess, a terminal member permanently connected to said plate and extending to the outside of the body, a compression resistance member in the recess in said body member, a

metallic base plate and a metallic face plate on opposite sides of said body member, a second terminal electrically connected to one of said plates, said last mentioned terminal being electrically connected to one side of said resistance member and said first mentioned terminal being connected to the opposite side HAROLD P. DONLE.

thereof. 

